Inspection system

ABSTRACT

A hand-mounted inspection system, configured to be mounted on a user&#39;s hand, comprising: an imaging unit, configured to provide images from at least one point of view located on the user&#39;s hand; and a measuring unit, configured to provide data relating to a physical property measured at a measurement location on the user&#39;s hand. The measuring unit includes a sensor configured to provide a measurement between two measurement locations, each of the two measurement locations being located on a digit of the user&#39;s hand, a tip of a digit of the user&#39;s hand, on the phalanges of a digit of a user&#39;s hand, on the palm of the user&#39;s hand or on the back of the user&#39;s hand.

CROSS-REFERENCE TO RELATED APPLICATIONS

This specification is based upon and claims the benefit of priority fromUnited Kingdom patent application number GB 1820117.8 filed on Dec. 11th2018, the entire contents of which are incorporated herein by reference.

BACKGROUND Field of the Disclosure

The present disclosure relates to the provision of an inspection systemsuitable for use in inspection and/or measurement in difficult-to-accessenvironments, such as gas turbine engines and/or engines provided toaircraft.

DESCRIPTION OF THE RELATED ART

Various inspection systems are known for inspecting and/or makingmeasurements in difficult-to-access environments e.g. within a gasturbine engine.

U.S. Pat. No. 9,126,243 B2 discloses a maintenance glove that is anarm-length glove made of a flexible material for performing maintenancework within sealed housings. An armhole-side end of the glove can beattached to a flange of a maintenance opening in a gas-tight manner andthe hand end of which is freely movable, wherein a hand-grip is locatedin the hand end. The hand end is telescopically extendable. A camera anda light source are located at the hand end. Furthermore tools and/orsensors are also located at the hand end.

United States patent application US 2018/0328808 A1 discloses a devicefor the detection of leaks and module for the detection of leaks. Thedevice is configured to check tightness of an object to be tested by atracer gas. The device includes a sniffing probe configured to beconnected to a leak detector and/or a spray blower configured to beconnected to a source of the tracer gas. It has a glove to which thesniffing probe and/or the spray blower is attached. The document alsodiscloses a module for detecting leaks that includes the aforementioneddevice that is configured to check the checking the tightness of theobject to be tested by the tracer gas.

A need remains for an improved inspection system or at least aninspection system that provides a useful alternative to known inspectionsystems.

SUMMARY

According to a first aspect there is provided a hand-mounted inspectionsystem, configured to be mounted on a user's hand, comprising an imagingunit, configured to provide images from at least one point of viewlocated on the user's hand; and a measuring unit, configured to providedata relating to a physical property measured at a measurement locationon the user's hand; wherein the measuring unit includes a sensorconfigured to provide a measurement between two measurement locations,each of the two measurement locations being located on a digit of theuser's hand, a tip of a digit of the user's hand, on the phalanges of adigit of a user's hand, on the palm of the user's hand or on the back ofthe user's hand.

The measuring unit, may comprise at least one of:

a sensor configured to measure a temperature at a measurement locationon a user's hand;

a sensor configured to measure a force exerted on a measurement locationon a user's hand;

a sensor configured to measure the acceleration of a measurementlocation on a user's hand;

a sensor configured to measure ionizing radiation at a measurementlocation on a user's hand;

a sensor configured to measure at least one of the direction andstrength of a magnetic field and/or an electric field at a measurementlocation on a user's hand;

a sensor configured to measure an eddy current in a material inproximity to a measurement location on a user's hand;

a sensor configured to detect sound waves at a measurement location on auser's hand;

a sensor configured to measure the separation between two measurementlocations on a user's hand; and

a sensor configured to measure at least one of the voltage, electriccurrent and the electrical resistance between two measurement locationson a user's hand.

In an arrangement, the measuring unit comprises a sensor configured toprovide a measurement between two measurement locations; and the twomeasurement locations are located at the tips of two different digits ofthe user's hand, optionally at the tip of the thumb of the user's handand the tip of a finger of the user's hand.

In an arrangement, at least two sensors measure or detect at the samemeasurement location.

The imaging unit may comprise at least one sub-unit providing imagesthat is at least one of:

-   -   a camera;    -   a 360° camera;    -   a wavelength filtered camera;    -   a thermal camera;    -   a zoom camera;    -   a macro camera;    -   a stereo camera;    -   a dichroic camera; and    -   an ultrasound receiver.

In an arrangement, at least one point of view of images provided by theimaging unit is located on a digit of the user's hand, on a tip of adigit of the user's hand, on the phalanges of a digit of a user's hand,on the palm of the user's hand or on the back of the user's hand.

In an arrangement, the imaging unit comprises at least two sub-unitsconfigured to provide images from different points of view.

In an arrangement, the at least two sub-units are a different type fromeach other.

In an arrangement, the hand-mounted inspection system may comprise acovering that encapsulates the user's hand.

The covering may extend to encapsulate at least a part of the forearm ofthe user and, optionally, at least a part of the upper arm of the user.

The covering may be formed from a material that is at least one of fluidimpermeable, gas impermeable, thermally resistant, electricallyresistant and puncture resistant.

In an arrangement, the hand-mounted inspection system may furthercomprise a fluid dispensing unit configured to supply a fluid from atleast one dispensing location located on the user's hand.

The at least one dispensing location may be located on a digit of theuser's hand, on a tip of a digit of the user's hand, on the phalanges ofa digit of a user's hand, on the palm of the user's hand or on the backof the user's hand.

The fluid dispensing unit may be configured to supply at least one ofoil, a liquid penetrant, an air jet and a water jet.

In an arrangement, the hand-mounted inspection system may furthercomprise a fluid absorbing unit configured to absorb fluid at a locationon at least one of a digit of the user's hand, a tip of a digit of theuser's hand, on the phalanges of a digit of a user's hand, the palm ofthe user's hand and the back of the user's hand.

In an arrangement, the hand-mounted inspection system may furthercomprise at least one illuminator, configured to emit at least one ofvisible light, infrared and ultraviolet radiation.

The illuminator may located on a digit of the user's hand, at the tip ofa digit of the user's hand, on the phalanges of a digit of a user'shand, on the palm of the user's hand or on the back of the user's hand.

In an arrangement, the hand-mounted inspection system may furthercomprise a controller, configured to receive data from at least one ofthe imaging unit and the measuring unit and to output correspondinginformation to a user interface.

The user interface may comprise at least one display configured todisplay an image based on data from the imaging unit.

In an arrangement, the hand-mounted inspection system is configured foruse within a machine, optionally for use with an aircraft propulsionsystem and/or a gas turbine engine or a hybrid gas/electric propulsionsystem.

In an arrangement, the hand-mounted inspection system is configured foruse within a human or animal body.

According to a second aspect there is provided a method of inspectingand/or servicing a machine, optionally an aircraft engine, comprisingmounting the hand-mounted system described above on a user's hand; andinserting the user's hand into the machine.

As noted elsewhere herein, the present disclosure may relate to a gasturbine engine. Such a gas turbine engine may comprise an engine corecomprising a turbine, a combustor, a compressor, and a core shaftconnecting the turbine to the compressor. Such a gas turbine engine maycomprise a fan (having fan blades) located upstream of the engine core.

Arrangements of the present disclosure may be particularly, although notexclusively, beneficial for fans that are driven via a gearbox.Accordingly, the gas turbine engine may comprise a gearbox that receivesan input from the core shaft and outputs drive to the fan so as to drivethe fan at a lower rotational speed than the core shaft. The input tothe gearbox may be directly from the core shaft, or indirectly from thecore shaft, for example via a spur shaft and/or gear. The core shaft mayrigidly connect the turbine and the compressor, such that the turbineand compressor rotate at the same speed (with the fan rotating at alower speed).

The gas turbine engine as described and/or claimed herein may have anysuitable general architecture. For example, the gas turbine engine mayhave any desired number of shafts that connect turbines and compressors,for example one, two or three shafts. Purely by way of example, theturbine connected to the core shaft may be a first turbine, thecompressor connected to the core shaft may be a first compressor, andthe core shaft may be a first core shaft. The engine core may furthercomprise a second turbine, a second compressor, and a second core shaftconnecting the second turbine to the second compressor. The secondturbine, second compressor, and second core shaft may be arranged torotate at a higher rotational speed than the first core shaft.

In such an arrangement, the second compressor may be positioned axiallydownstream of the first compressor. The second compressor may bearranged to receive (for example directly receive, for example via agenerally annular duct) flow from the first compressor.

The gearbox may be arranged to be driven by the core shaft that isconfigured to rotate (for example in use) at the lowest rotational speed(for example the first core shaft in the example above). For example,the gearbox may be arranged to be driven only by the core shaft that isconfigured to rotate (for example in use) at the lowest rotational speed(for example only be the first core shaft, and not the second coreshaft, in the example above). Alternatively, the gearbox may be arrangedto be driven by any one or more shafts, for example the first and/orsecond shafts in the example above.

The gearbox is a reduction gearbox (in that the output to the fan is alower rotational rate than the input from the core shaft). Any type ofgearbox may be used. For example, the gearbox may be a “planetary” or“star” gearbox, as described in more detail elsewhere herein. Thegearbox may have any desired reduction ratio (defined as the rotationalspeed of the input shaft divided by the rotational speed of the outputshaft), for example greater than 2.5, for example in the range of from 3to 4.2, for example on the order of or at least 3, 3.1, 3.2, 3.3, 3.4,3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1 or 4.2. The gear ratio may be, forexample, between any two of the values in the previous sentence. Ahigher gear ratio may be more suited to “planetary” style gearbox. Insome arrangements, the gear ratio may be outside these ranges.

In any gas turbine engine as described and/or claimed herein, acombustor may be provided axially downstream of the fan andcompressor(s). For example, the combustor may be directly downstream of(for example at the exit of) the second compressor, where a secondcompressor is provided. By way of further example, the flow at the exitto the combustor may be provided to the inlet of the second turbine,where a second turbine is provided. The combustor may be providedupstream of the turbine(s).

The or each compressor (for example the first compressor and secondcompressor as described above) may comprise any number of stages, forexample multiple stages. Each stage may comprise a row of rotor bladesand a row of stator vanes, which may be variable stator vanes (in thattheir angle of incidence may be variable). The row of rotor blades andthe row of stator vanes may be axially offset from each other.

The or each turbine (for example the first turbine and second turbine asdescribed above) may comprise any number of stages, for example multiplestages. Each stage may comprise a row of rotor blades and a row ofstator vanes. The row of rotor blades and the row of stator vanes may beaxially offset from each other.

Each fan blade may be defined as having a radial span extending from aroot (or hub) at a radially inner gas-washed location, or 0% spanposition, to a tip at a 100% span position. The ratio of the radius ofthe fan blade at the hub to the radius of the fan blade at the tip maybe less than (or on the order of) any of: 0.4, 0.39, 0.38 0.37, 0.36,0.35, 0.34, 0.33, 0.32, 0.31, 0.3, 0.29, 0.28, 0.27, 0.26, or 0.25. Theratio of the radius of the fan blade at the hub to the radius of the fanblade at the tip may be in an inclusive range bounded by any two of thevalues in the previous sentence (i.e. the values may form upper or lowerbounds). These ratios may commonly be referred to as the hub-to-tipratio. The radius at the hub and the radius at the tip may both bemeasured at the leading edge (or axially forwardmost) part of the blade.The hub-to-tip ratio refers, of course, to the gas-washed portion of thefan blade, i.e. the portion radially outside any platform.

The radius of the fan may be measured between the engine centreline andthe tip of a fan blade at its leading edge. The fan diameter (which maysimply be twice the radius of the fan) may be greater than (or on theorder of) any of: 250 cm (around 100 inches), 260 cm, 270 cm (around 105inches), 280 cm (around 110 inches), 290 cm (around 115 inches), 300 cm(around 120 inches), 310 cm, 320 cm (around 125 inches), 330 cm (around130 inches), 340 cm (around 135 inches), 350 cm, 360 cm (around 140inches), 370 cm (around 145 inches), 380 (around 150 inches) cm or 390cm (around 155 inches). The fan diameter may be in an inclusive rangebounded by any two of the values in the previous sentence (i.e. thevalues may form upper or lower bounds).

The rotational speed of the fan may vary in use. Generally, therotational speed is lower for fans with a higher diameter. Purely by wayof non-limitative example, the rotational speed of the fan at cruiseconditions may be less than 2500 rpm, for example less than 2300 rpm.Purely by way of further non-limitative example, the rotational speed ofthe fan at cruise conditions for an engine having a fan diameter in therange of from 250 cm to 300 cm (for example 250 cm to 280 cm) may be inthe range of from 1700 rpm to 2500 rpm, for example in the range of from1800 rpm to 2300 rpm, for example in the range of from 1900 rpm to 2100rpm. Purely by way of further non-limitative example, the rotationalspeed of the fan at cruise conditions for an engine having a fandiameter in the range of from 320 cm to 380 cm may be in the range offrom 1200 rpm to 2000 rpm, for example in the range of from 1300 rpm to1800 rpm, for example in the range of from 1400 rpm to 1600 rpm.

In use of the gas turbine engine, the fan (with associated fan blades)rotates about a rotational axis. This rotation results in the tip of thefan blade moving with a velocity U_(tip). The work done by the fanblades 13 on the flow results in an enthalpy rise dH of the flow. A fantip loading may be defined as dH/U_(tip) ², where dH is the enthalpyrise (for example the 1-D average enthalpy rise) across the fan andU_(tip) is the (translational) velocity of the fan tip, for example atthe leading edge of the tip (which may be defined as fan tip radius atleading edge multiplied by angular speed). The fan tip loading at cruiseconditions may be greater than (or on the order of) any of: 0.3, 0.31,0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39 or 0.4 (all units in thisparagraph being Jkg⁻¹K⁻¹/(ms⁻¹)²). The fan tip loading may be in aninclusive range bounded by any two of the values in the previoussentence (i.e. the values may form upper or lower bounds).

Gas turbine engines in accordance with the present disclosure may haveany desired bypass ratio, where the bypass ratio is defined as the ratioof the mass flow rate of the flow through the bypass duct to the massflow rate of the flow through the core at cruise conditions. In somearrangements the bypass ratio may be greater than (or on the order of)any of the following: 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5,15, 15.5, 16, 16.5, or 17. The bypass ratio may be in an inclusive rangebounded by any two of the values in the previous sentence (i.e. thevalues may form upper or lower bounds). The bypass duct may besubstantially annular. The bypass duct may be radially outside theengine core. The radially outer surface of the bypass duct may bedefined by a nacelle and/or a fan case.

The overall pressure ratio of a gas turbine engine as described and/orclaimed herein may be defined as the ratio of the stagnation pressureupstream of the fan to the stagnation pressure at the exit of thehighest pressure compressor (before entry into the combustor). By way ofnon-limitative example, the overall pressure ratio of a gas turbineengine as described and/or claimed herein at cruise may be greater than(or on the order of) any of the following: 35, 40, 45, 50, 55, 60, 65,70, 75. The overall pressure ratio may be in an inclusive range boundedby any two of the values in the previous sentence (i.e. the values mayform upper or lower bounds).

Specific thrust of an engine may be defined as the net thrust of theengine divided by the total mass flow through the engine. At cruiseconditions, the specific thrust of an engine described and/or claimedherein may be less than (or on the order of) any of the following: 110Nkg⁻¹s, 105 Nkg⁻¹s, 100 Nkg⁻¹s, 95 Nkg⁻¹s, 90 Nkg⁻¹s, 85 Nkg⁻¹s or 80Nkg⁻¹s. The specific thrust may be in an inclusive range bounded by anytwo of the values in the previous sentence (i.e. the values may formupper or lower bounds). Such engines may be particularly efficient incomparison with conventional gas turbine engines.

A gas turbine engine as described and/or claimed herein may have anydesired maximum thrust. Purely by way of non-limitative example, a gasturbine as described and/or claimed herein may be capable of producing amaximum thrust of at least (or on the order of) any of the following:160 kN, 170 kN, 180 kN, 190 kN, 200 kN, 250 kN, 300 kN, 350 kN, 400 kN,450 kN, 500 kN, or 550 kN. The maximum thrust may be in an inclusiverange bounded by any two of the values in the previous sentence (i.e.the values may form upper or lower bounds). The thrust referred to abovemay be the maximum net thrust at standard atmospheric conditions at sealevel plus 15° C. (ambient pressure 101.3 kPa, temperature 30° C.), withthe engine static.

In use, the temperature of the flow at the entry to the high pressureturbine may be particularly high. This temperature, which may bereferred to as TET, may be measured at the exit to the combustor, forexample immediately upstream of the first turbine vane, which itself maybe referred to as a nozzle guide vane. At cruise, the TET may be atleast (or on the order of) any of the following: 1400K, 1450K, 1500K,1550K, 1600K or 1650K. The TET at cruise may be in an inclusive rangebounded by any two of the values in the previous sentence (i.e. thevalues may form upper or lower bounds). The maximum TET in use of theengine may be, for example, at least (or on the order of) any of thefollowing: 1700K, 1750K, 1800K, 1850K, 1900K, 1950K or 2000K. Themaximum TET may be in an inclusive range bounded by any two of thevalues in the previous sentence (i.e. the values may form upper or lowerbounds). The maximum TET may occur, for example, at a high thrustcondition, for example at a maximum take-off (MTO) condition.

A fan blade and/or aerofoil portion of a fan blade described and/orclaimed herein may be manufactured from any suitable material orcombination of materials. For example at least a part of the fan bladeand/or aerofoil may be manufactured at least in part from a composite,for example a metal matrix composite and/or an organic matrix composite,such as carbon fibre. By way of further example at least a part of thefan blade and/or aerofoil may be manufactured at least in part from ametal, such as a titanium based metal or an aluminium based material(such as an aluminium-lithium alloy) or a steel based material. The fanblade may comprise at least two regions manufactured using differentmaterials. For example, the fan blade may have a protective leadingedge, which may be manufactured using a material that is better able toresist impact (for example from birds, ice or other material) than therest of the blade. Such a leading edge may, for example, be manufacturedusing titanium or a titanium-based alloy. Thus, purely by way ofexample, the fan blade may have a carbon-fibre or aluminium based body(such as an aluminium lithium alloy) with a titanium leading edge.

A fan as described and/or claimed herein may comprise a central portion,from which the fan blades may extend, for example in a radial direction.The fan blades may be attached to the central portion in any desiredmanner. For example, each fan blade may comprise a fixture which mayengage a corresponding slot in the hub (or disc).

Purely by way of example, such a fixture may be in the form of adovetail that may slot into and/or engage a corresponding slot in thehub/disc in order to fix the fan blade to the hub/disc. By way offurther example, the fan blades may be formed integrally with a centralportion. Such an arrangement may be referred to as a blisk or a bling.Any suitable method may be used to manufacture such a blisk or bling.For example, at least a part of the fan blades may be machined from ablock and/or at least part of the fan blades may be attached to thehub/disc by welding, such as linear friction welding.

The gas turbine engines described and/or claimed herein may or may notbe provided with a variable area nozzle (VAN). Such a variable areanozzle may allow the exit area of the bypass duct to be varied in use.The general principles of the present disclosure may apply to engineswith or without a VAN.

The fan of a gas turbine as described and/or claimed herein may have anydesired number of fan blades, for example 14, 16, 18, 20, 22, 24 or 26fan blades.

As used herein, cruise conditions may mean cruise conditions of anaircraft to which the gas turbine engine is attached. Such cruiseconditions may be conventionally defined as the conditions atmid-cruise, for example the conditions experienced by the aircraftand/or engine at the midpoint (in terms of time and/or distance) betweentop of climb and start of decent.

Purely by way of example, the forward speed at the cruise condition maybe any point in the range of from Mach 0.7 to 0.9, for example 0.75 to0.85, for example 0.76 to 0.84, for example 0.77 to 0.83, for example0.78 to 0.82, for example 0.79 to 0.81, for example on the order of Mach0.8, on the order of Mach 0.85 or in the range of from 0.8 to 0.85. Anysingle speed within these ranges may be the cruise condition. For someaircraft, the cruise conditions may be outside these ranges, for examplebelow Mach 0.7 or above Mach 0.9.

Purely by way of example, the cruise conditions may correspond tostandard atmospheric conditions at an altitude that is in the range offrom 10000 m to 15000 m, for example in the range of from 10000 m to12000 m, for example in the range of from 10400 m to 11600 m (around38000 ft), for example in the range of from 10500 m to 11500 m, forexample in the range of from 10600 m to 11400 m, for example in therange of from 10700 m (around 35000 ft) to 11300 m, for example in therange of from 10800 m to 11200 m, for example in the range of from 10900m to 11100 m, for example on the order of 11000 m. The cruise conditionsmay correspond to standard atmospheric conditions at any given altitudein these ranges.

Purely by way of example, the cruise conditions may correspond to: aforward Mach number of 0.8; a pressure of 23000 Pa; and a temperature of−55° C.

As used anywhere herein, “cruise” or “cruise conditions” may mean theaerodynamic design point. Such an aerodynamic design point (or ADP) maycorrespond to the conditions (comprising, for example, one or more ofthe Mach Number, environmental conditions and thrust requirement) forwhich the fan is designed to operate. This may mean, for example, theconditions at which the fan (or gas turbine engine) is designed to haveoptimum efficiency.

In use, a gas turbine engine described and/or claimed herein may operateat the cruise conditions defined elsewhere herein. Such cruiseconditions may be determined by the cruise conditions (for example themid-cruise conditions) of an aircraft to which at least one (for example2 or 4) gas turbine engine may be mounted in order to provide propulsivethrust.

The skilled person will appreciate that except where mutually exclusive,a feature or parameter described in relation to any one of the aboveaspects may be applied to any other aspect. Furthermore, except wheremutually exclusive, any feature or parameter described herein may beapplied to any aspect and/or combined with any other feature orparameter described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described by way of example only, with referenceto the Figures, in which:

FIG. 1 is a sectional side view of a gas turbine engine;

FIG. 2 is a close up sectional side view of an upstream portion of a gasturbine engine;

FIG. 3 is a partially cut-away view of a gearbox for a gas turbineengine;

FIGS. 4 to 6 depict examples of hand-mounted inspection systemsaccording to the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

Aspects and embodiments of the present disclosure will now be discussedwith reference to the accompanying figures. Further aspects andembodiments will be apparent to those skilled in the art.

FIG. 1 illustrates a gas turbine engine 10 having a principal rotationalaxis 9. The engine 10 comprises an air intake 12 and a propulsive fan 23that generates two airflows: a core airflow A and a bypass airflow B.The gas turbine engine 10 comprises a core 11 that receives the coreairflow A. The engine core 11 comprises, in axial flow series, a lowpressure compressor 14, a high-pressure compressor 15, combustionequipment 16, a high-pressure turbine 17, a low pressure turbine 19 anda core exhaust nozzle 20. A nacelle 21 surrounds the gas turbine engine10 and defines a bypass duct 22 and a bypass exhaust nozzle 18. Thebypass airflow B flows through the bypass duct 22. The fan 23 isattached to and driven by the low pressure turbine 19 via a shaft 26 andan epicyclic gearbox 30.

In use, the core airflow A is accelerated and compressed by the lowpressure compressor 14 and directed into the high pressure compressor 15where further compression takes place. The compressed air exhausted fromthe high pressure compressor 15 is directed into the combustionequipment 16 where it is mixed with fuel and the mixture is combusted.The resultant hot combustion products then expand through, and therebydrive, the high pressure and low pressure turbines 17, 19 before beingexhausted through the core exhaust nozzle 20 to provide some propulsivethrust. The high pressure turbine 17 drives the high pressure compressor15 by a suitable interconnecting shaft 27. The fan 23 generally providesthe majority of the propulsive thrust. The epicyclic gearbox 30 is areduction gearbox.

An exemplary arrangement for a geared fan gas turbine engine 10 is shownin FIG. 2. The low pressure turbine 19 (see FIG. 1) drives the shaft 26,which is coupled to a sun wheel, or sun gear, 28 of the epicyclic geararrangement 30. Radially outwardly of the sun gear 28 and intermeshingtherewith is a plurality of planet gears 32 that are coupled together bya planet carrier 34. The planet carrier 34 constrains the planet gears32 to precess around the sun gear 28 in synchronicity whilst enablingeach planet gear 32 to rotate about its own axis. The planet carrier 34is coupled via linkages 36 to the fan 23 in order to drive its rotationabout the engine axis 9. Radially outwardly of the planet gears 32 andintermeshing therewith is an annulus or ring gear 38 that is coupled,via linkages 40, to a stationary supporting structure 24.

Note that the terms “low pressure turbine” and “low pressure compressor”as used herein may be taken to mean the lowest pressure turbine stagesand lowest pressure compressor stages (i.e. not including the fan 23)respectively and/or the turbine and compressor stages that are connectedtogether by the interconnecting shaft 26 with the lowest rotationalspeed in the engine (i.e. not including the gearbox output shaft thatdrives the fan 23). In some literature, the “low pressure turbine” and“low pressure compressor” referred to herein may alternatively be knownas the “intermediate pressure turbine” and “intermediate pressurecompressor”. Where such alternative nomenclature is used, the fan 23 maybe referred to as a first, or lowest pressure, compression stage.

The epicyclic gearbox 30 is shown by way of example in greater detail inFIG. 3. Each of the sun gear 28, planet gears 32 and ring gear 38comprise teeth about their periphery to intermesh with the other gears.However, for clarity only exemplary portions of the teeth areillustrated in FIG. 3. There are four planet gears 32 illustrated,although it will be apparent to the skilled reader that more or fewerplanet gears 32 may be provided within the scope of the claimedinvention. Practical applications of a planetary epicyclic gearbox 30generally comprise at least three planet gears 32.

The epicyclic gearbox 30 illustrated by way of example in FIGS. 2 and 3is of the planetary type, in that the planet carrier 34 is coupled to anoutput shaft via linkages 36, with the ring gear 38 fixed. However, anyother suitable type of epicyclic gearbox 30 may be used. By way offurther example, the epicyclic gearbox 30 may be a star arrangement, inwhich the planet carrier 34 is held fixed, with the ring (or annulus)gear 38 allowed to rotate. In such an arrangement the fan 23 is drivenby the ring gear 38. By way of further alternative example, the gearbox30 may be a differential gearbox in which the ring gear 38 and theplanet carrier 34 are both allowed to rotate.

It will be appreciated that the arrangement shown in FIGS. 2 and 3 is byway of example only, and various alternatives are within the scope ofthe present disclosure. Purely by way of example, any suitablearrangement may be used for locating the gearbox 30 in the engine 10and/or for connecting the gearbox 30 to the engine 10. By way of furtherexample, the connections (such as the linkages 36, 40 in the FIG. 2example) between the gearbox 30 and other parts of the engine 10 (suchas the input shaft 26, the output shaft and the fixed structure 24) mayhave any desired degree of stiffness or flexibility. By way of furtherexample, any suitable arrangement of the bearings between rotating andstationary parts of the engine (for example between the input and outputshafts from the gearbox and the fixed structures, such as the gearboxcasing) may be used, and the disclosure is not limited to the exemplaryarrangement of FIG. 2. For example, where the gearbox 30 has a stararrangement (described above), the skilled person would readilyunderstand that the arrangement of output and support linkages andbearing locations would typically be different to that shown by way ofexample in FIG. 2.

Accordingly, the present disclosure extends to a gas turbine enginehaving any arrangement of gearbox styles (for example star orplanetary), support structures, input and output shaft arrangement, andbearing locations.

Optionally, the gearbox may drive additional and/or alternativecomponents (e.g. the intermediate pressure compressor and/or a boostercompressor).

Other gas turbine engines to which the present disclosure may be appliedmay have alternative configurations. For example, such engines may havean alternative number of compressors and/or turbines and/or analternative number of interconnecting shafts. By way of further example,the gas turbine engine shown in FIG. 1 has a split flow nozzle 18, 20meaning that the flow through the bypass duct 22 has its own nozzle 18that is separate to and radially outside the core exhaust nozzle 20.However, this is not limiting, and any aspect of the present disclosuremay also apply to engines in which the flow through the bypass duct 22and the flow through the core 11 are mixed, or combined, before (orupstream of) a single nozzle, which may be referred to as a mixed flownozzle. One or both nozzles (whether mixed or split flow) may have afixed or variable area. Whilst the described example relates to aturbofan engine, the disclosure may apply, for example, to any type ofgas turbine engine, such as an open rotor (in which the fan stage is notsurrounded by a nacelle) or turboprop engine, for example. In somearrangements, the gas turbine engine 10 may not comprise a gearbox 30.

The geometry of the gas turbine engine 10, and components thereof, isdefined by a conventional axis system, comprising an axial direction(which is aligned with the rotational axis 9), a radial direction (inthe bottom-to-top direction in FIG. 1), and a circumferential direction(perpendicular to the page in the FIG. 1 view). The axial, radial andcircumferential directions are mutually perpendicular.

The present disclosure provides an inspection system that ishand-mounted. It may include a variety of units that are mounted to theuser's hand. Such an arrangement may therefore exploit the versatilityof human hands and arms in order to gain access to locations that arehard to reach. Such an arrangement may also be more intuitive to a userand/or easier to control than, for example, an endoscope. Endoscopes mayhave limitations due to their poor stiffness, which makes them difficultto steer over long distances, and limiting mobility. Such an arrangementmay also benefit from the experience of expert technicians andengineers, in effect extending their senses.

An arrangement of a hand-mounted inspection system may include at leastone imaging unit and at least one measuring unit. The imaging unit mayprovide images from at least one point of view located on the user'shand and the measuring unit may provide data relating to a physicalproperty measured at a measurement location on the user's hand. Thecombination of an imaging unit and a measuring unit may enable improvedinspection, namely providing measurement data in addition to enabling avisual inspection. Furthermore, the use of the imaging unit may assistin guiding the user to insert their hand to a required location and mayassist in ensuring that the measuring unit obtains a measurement at adesired measurement location.

The measurement unit may have one or more of a plurality of sensors. Asdiscussed below, the sensors may be configured to provide data relatingto a physical property measured or detected at a measurement location ona user's hand. The measurement location may be at a tip of a digit,namely a finger or thumb, of a user's hand, at another location on adigit of the user's hand such as on the phalanges, on the palm of theuser's hand, for example in the middle of the palm or on an edge of thepalm at which the fingers join the palm of the user's hand, or on theback of the user's hand. Some sensors may be configured to providemeasurements between two such measurement locations. It should also beappreciated that, where a measuring unit has a plurality of sensors,each sensor may measure or detect a physical property at differentmeasurement locations. Alternatively, in some arrangements, two or moresensors may measure or detect respective physical properties at the samemeasurement location.

In an arrangement, the measuring unit may include a sensor configured tomeasure a temperature at a measurement location on a user's hand. Forexample, a thermometer, such as an electric thermometer may be provided.Accordingly, a user may touch the part of the hand-mounted inspectionsystem containing the sensor, to an item, such as a component within theapparatus being inspected, in order to measure the temperature of thatcomponent. Alternatively or additionally, the thermometer may be used toprovide a warning to a user if the environmental temperature risksinjury to the user.

In an arrangement, the measuring unit may include a sensor configured tomeasure a force exerted on a measurement location on a user's hand. Sucha sensor may be used to enable an operator to determine whether flexiblecomponents in an apparatus have the correct stiffness or whether theyare loose or damaged. Examples of such a force sensor may includeresistive touch pads that change electrical resistance when pressed,capacitive touch pads that change charge capacity when pressed and/orflexible structures with embedded strain sensors. Force sensors may alsobe used to store touch data to be played back using haptic devices fortechnician and engineer training.

In an arrangement, the measuring unit may comprise a sensor configuredto measure the acceleration and/or position of a measurement location ona user's hand. This may include the use of accelerometers, for examplethat may be used in an inertial measurement unit, namely an arrangementtracking the movement of the measurement location relative to a startinglocation. If the starting location is known, subsequent locations maytherefore be determined. This may enable tracking position of thehand-mounted inspection system relative to the user and/or within anapparatus being inspected.

Sensors configured to measure acceleration and/or position of ameasurement location may also be configured to provide measurementsrelative to a fixed point within the hand-mounted inspection systemand/or relative to another measurement location. Such sensors mayinclude flex sensors, configured to change electrical properties whenflexed, strain sensors, configured to change electrical properties whenstretched, optical fibre sensors, such as a fibre Bragg grating sensorsproviding measurements of strain and position, rotary encoders that maybe positioned at a joint of the user's hand to measure movement ofdigits relative to the hand, and string or linear encoders positioned atthe end of tendons connected to fingers or joints.

In an arrangement, the use of sensors such as those discussed above maybe configured in order to provide a measurement of the separationbetween two measurement locations on a user's hand. For example, such asensor may be configured to measure the separation between the tips oftwo digits, such as between the tip of a finger and the tip of a thumbof the user. Accordingly, the user may position their hand within anapparatus and measure the separation between two parts. For example, ifthe sensor is configured to measure the separation between the tips ofthe thumb and forefinger, a user may hold a component between the thumband forefinger and obtain a measurement of the size of the component.

In an arrangement, the measuring unit may comprise a sensor configuredto measure ionising radiation at a measurement location on the user'shand. For example, the sensor may be a Geiger counter. Provision of sucha sensor may improve the safety of an operator required to inspect anapparatus in which there is a risk of elevated levels of radiation.Alternatively or additionally, a deviation from an expected level ofradiation may indicate a fault within a system, even if it poses nosafety threat to the operator.

In an arrangement, the measuring unit may comprise a sensor configuredto measure at least one of the direction and the strength of a magneticfield at a measurement location on the user's hand. For example, amagnetometer may be provided that may facilitate the inspection ofelectrical components and/or residual magnetism in components. In anarrangement, the measuring unit may include a sensor configured tomeasure at least one of the direction and strength of an electric fieldat a measurement location on the user's hand. In an arrangement, asensor may in particular be configured to detect eddy currents in amaterial in proximity to measurement location on a user's hand.

In an arrangement, the measuring unit may include a sensor configured todetect soundwaves at a measurement location on a user's hand. This mayinclude a microphone, which may detect audible sounds, such as creakingor scraping sounds that may be indicative of the condition of theapparatus and/or indicative of faults within an apparatus. Alternativelyor additionally, the sensor may be configured to detect ultrasonicsoundwaves, for example for ultrasonic non-destructive testing that maybe used to detect internal flaws in components, such as cracking ordelamination.

In an arrangement, the measuring unit may include a sensor configured tomeasure at least one of voltage, electric current, and the electricalresistance between two measurement locations on a user's hand. Forexample, such a sensor may be configured to provide a measurementbetween the tips of two digits on the user's hand, for example betweenthe tips of the thumb and forefinger. Accordingly, in use, a user maysimply touch the tips of the two digits to two different parts of theapparatus being inspected in order to obtain a desired measurement ofthe electrical voltage, electric current and/or electrical resistancebetween the two parts. This may be significantly easier thanmanipulating two probes into an apparatus and holding each against adifferent part of the apparatus.

Similarly to the measuring unit, the imaging unit may have any one ormore of a plurality of different imaging sub-units. The sub-units mayeach be configured to provide images from a point of view located on adigit of the user's hand. For example, the point of view may be on thethumb or finger, specifically on the phalanges or tip of a digit, on thepalm of the user's hand, for example in the middle of the palm or on anedge such as the edge at which the fingers join the palm, or on the backof the user's hand.

Where an imaging unit has multiple sub-units providing images, eachsub-unit may provide images having differing locations of point of view.Alternatively or additionally, two or more sub-units may provide imageshaving a common point of view. In either case, the sub-units of theimaging unit may all be of different types, as discussed below, or atleast two, may be the same, for example providing images from differentpoints of view.

One or more of the sub-units providing images may be a camera that mayenable intuitive manual inspection of the apparatus and/or may assist inguiding the user's hand into the apparatus. It should be appreciatedthat a camera may be configured to provide a colour image or amonochrome image. Where plural cameras are provided, the images providedby each may be provided separately to a user as discussed further belowand/or the images may be joined, using software within a controller asdiscussed below, in order to increase the field of view. The use ofplural images from different points of view may also be used to computethe distances by using stereovision.

In an arrangement, a sub-unit of the imaging unit may comprise a 360°camera, such as a dual-lens 360° camera. Such a camera may be placed,for example, on the tip of a finger such as the index finger to providea full immersive view of the environment around the hand-mountedinspection system.

In an arrangement, a sub-unit of the imaging unit may include awavelength filtered camera, configured to capture specific wavelengthsof visible, infrared or ultraviolet light. Such a sub-unit may be usedfor inspection of particular phenomena such as florescence or radiativeluminescence.

In an arrangement, a sub-unit of the imaging unit may comprise a thermalcamera, configured to detect heat emissions from objects within thefield of view. Such a sub-unit may be useful for warning a user ifcomponents are hot. It may also be useful for identifying componentsthat have been subject to unintended wear, which may result infrictional heating.

In an arrangement, a sub-unit of the imaging unit may include a zoomcamera, namely a camera with high or variable magnification. This mayassist in inspection of components that the hand-mounted inspectionsystem cannot closely approach.

In an arrangement, a sub-unit of the imaging unit may include amacrocamera, configured to provide high quality images of componentsthat are close to the hand-mounted inspection system, enabling close upinspection of a component.

In an arrangement, a sub-unit of the imaging unit may include astereocamera, in which two cameras are provided that are set apart butrigidly connected at a known separation. Such a camera may provide 3Dimages to a user via a suitably configured display apparatus.Alternatively or additionally, a stereocamera may be used to measure thedistance to objects within the field of view. By measuring the distanceto two different objects, it may be possible to determine the separationbetween the two objects.

In an arrangement, a sub-unit of the imaging unit may include a camerawith an image splitting optical element capable of splitting componentsof light (such as wavelength or polarisation) in two or more directions,such as by using a dichroic filter beam splitter or a polarising filterbeam splitter. A camera fitted with a dichroic, polarising or other beamsplitter may for example be used to simultaneously view features infront of and behind the hand. A dichroic filter is a mirror that allowssome wavelengths of light to go through the glass and some to bereflected. Hence, with a dichroic filter placed in front of the camerasensor and at 45 degrees inclination, the camera can see through themirror in the wavelengths that can pass and can see the sidewaysreflection on the wavelengths that cannot pass. The same is true forselective polarisation splitters. Cubic prism wavelength splitters canbe used to separate red green and blue light arriving at a sensor, fromthe left, forward and right directions (for example), which could beused to give a user views in directions towards which fingers cannotnaturally bend.

In an arrangement, a sub-unit of the imaging unit may comprise anultrasound receiver. This may, for example, enable the generation ofimages showing the results of ultrasound testing, such asnon-destructive testing of welds and/or other parts of a component thatmay be subject to cracking or delamination.

In an arrangement, the hand-mounted inspection system may include acovering that encapsulates at least the user's hand. For example, thehand-mounted inspection system may include a glove, to which the othercomponents of the hand-mounted inspection system may be mounted. Such acovering may provide protection for the user's hand. For example, thecovering may be formed from a material that is at least one of fluidimpermeable, gas impermeable, thermally resistant, electricallyresistant and puncture resistant.

In this context, it should be understood that a thermally resistantmaterial may be a material that reduces thermal transfer to the user'shand to a level that should avoid injury when the hand-mountedinspection system is exposed to temperatures that may be expected withinan apparatus to be inspected by the inspection system, includingtemperatures that may be anticipated in the event of a malfunction ofthe apparatus. Similarly, an electrically resistant material may be onethat is expected to prevent a user from receiving an electric shockunder conditions expected in the apparatus to be inspected by thehand-mounted inspection system.

A puncture resistant material may be one that is expected to resistpenetration by a sharp object under forces that may be exerted on thehand-mounted inspection system during use within an apparatus to beinspected.

In an arrangement, the covering may be configured to be tight-fitting.This may enable the user to insert their hand and the hand-mountedinspection system into small spaces. Furthermore, having the coveringfit tightly and/or selecting a material that is smooth or at leasttightly woven, may prevent loose material from catching on sharp edges,which may potentially trap the user's hand within the apparatus.

In an arrangement, the covering may be extended to encapsulate at leasta part of the forearm of the user. It may extend up to or above theelbow of the user and may cover some or all of the upper arm of theuser. Such an arrangement of a covering may provide protection for theuser's arm as well as their hand when inserting the hand-mountedinspection system deep into an apparatus.

In an arrangement, the hand-mounted inspection system may include afluid dispensing unit configured to supply at least one fluid from atleast one dispensing location located on the user's hand. The dispensinglocations from which the dispensing unit may be configured to supplyfluid may include one or more of the digits of the user's hand, on thetip of a digit of the user's hand, on the phalanges of a digit of auser's hand, on the palm of the user's hand or on the back of the user'shand. Where the fluid dispensing unit is configured to supply fluid frommore than one dispensing location, it should be appreciated that thesame fluid may be supplied from more than one dispensing location and/ordifferent fluids may be supplied from different dispensing locations.

The fluid dispensing unit may be configured to supply oil, for exampleto function as a couplant, namely a layer of fluid to couple a componentto be inspected to an ultrasonic probe, or lubricate a part of anapparatus. Alternatively or additionally, the fluid dispensing unit maybe configured to supply a liquid penetrant. For example, a fluorescentliquid may be supplied for crack detection, weld inspection or similarpurposes. Alternatively or additionally, the fluid dispensing unit maybe configured to supply an air jet and/or a water jet that may be usedto clean a component and/or remove debris.

In an arrangement, a hand-mounted inspection system may include a fluidabsorbing unit that is arranged to absorb fluid at least one location ona user's hand, for example on a digit of the user's hand, specificallyat a tip of a digit of the user's hand and/or on the phalanges of adigit of the user's hand, on the palm of the user's hand and/or on theback of the user's hand. The fluid absorbing unit may be formed simplyby a sponge that absorbs fluid. Alternatively or additionally, a suctionsystem may be provided that removes the fluid.

In an arrangement, the hand-mounted inspection system may include atleast one illuminator. Such an illuminator may emit one or more ofvisible light, infrared radiation and ultraviolet radiation. In general,the illuminator may be used to illuminate components within theapparatus being inspected by the hand-mounted inspection system. Forexample, an ultraviolet radiation illuminator may be used to illuminatecomponents to which a fluorescent penetrant has been applied in order toinvestigate the existence of cracks and/or weld defects.

It will be appreciated that one or more illuminators may be provided atany of a plurality of locations on the user's hand, for example on adigit of the user's hand, optionally at the tip of a digit or on thephalanges of a digit of a user's hand, on the palm of the user's hand oron the back of the user's hand.

The hand-mounted inspection system may also include a controller. Thecontroller may receive data from the imaging unit and/or the measuringunit and output corresponding information to a user interface, such as adisplay. It should be appreciated that the connection between theimaging unit and/or the measuring unit and the controller may be by anysuitable means, including cables, optical fibres or a wirelessconnection such as Bluetooth or Wi-fi. The controller may be configuredalso to be worn by the operator, for example as a back-pack, waist bagor satchel, depending on the size of the controller. Likewise a powersupply for the hand-mounted inspection system may similarly also be wornby the user. This may enable the overall system to be mobile.Alternatively or additionally, the controller and/or power supply may beprovided separately.

The user interface may include at least one display configured such thatit can display an image based on data from the imaging unit. For asystem in which the imaging unit comprises a plurality of sub-units,each configured to generate respective images, plural displays may beprovided such that a user may view plural images at the same time and/orthe user interface may be configured such that a user can switch betweenplural image sources on a single display.

The user interface may include at least one head-mounted display such asa virtual reality headset. For a system in which the imaging unitcomprises a camera or a plurality of cameras that returnthree-dimensional data, the head-mounted display may be used to give theuser the appearance of being immersed in the environment. Alternativelyor additionally, for a system in which the imaging unit comprises twocameras a fixed distance apart, such as a stereocamera, a head-mounteddisplay may be used to display the image of a first camera to a firsteye and the image of a second camera to a second eye, giving the usernatural-feeling depth perception within the environment.

In an arrangement, the controller and/or the user interface may beconfigured such that images displayed with overlaid additional imagesand/or information to provide an augmented reality display. The use ofaugmented reality may, for example, enable the display of measurementvalues, interesting features, highlight likely locations of damage ordisplay names of components.

Although the above description has related to the provision of ahand-mounted inspection system for use within a machine, such as anaircraft propulsion system, which may be a gas turbine engine or, forexample, a hybrid gas-electric propulsion system, it should beappreciated that variations of the hand-mounted inspection system may besuitable for other uses.

For example, a hand-mounted inspection system may be configured for usewithin a human or animal body. It should be appreciated that ahand-mounted inspection system for such a different use may differ fromone for use within a machine. By way of example only, it should beappreciated that the requirements for a covering, where used, woulddiffer. For example, there would likely be no requirement for thecovering of a hand-mounted inspection system for use within a human oranimal body, where used, to be thermally resistant and/or electricallyresistant. However, it would likely be desirable for covering to be atleast fluid impermeable to separate the user's hand from blood withinthe human or animal body being inspected. As a further example, a sensorconfigured to detect sound waves for use within a hand-mountedinspection system to be used within a human or animal body may bespecifically configured to detect characteristic sounds that may beexpected within a human or animal body, such as sounds of breathing,heartbeats, and/or muscular convulsions.

FIG. 4 depicts an example of a hand-mounted inspection system. In thisarrangement, a glove shaped covering 50 is provided to encapsulate auser's hand. The measuring unit 60 includes a sensor in the form of athermometer 61 mounted to the back of the hand and a sensor in the formof an ultrasonic probe 62 mounted to the tip of the thumb. Measuringunit 60 also includes a plurality of position sensors 63, mounted to thephalanges of each of the digits and to plural locations on the back ofthe hand, providing information on the position of each part of thehand.

The imaging unit 70 of the inspection system shown in FIG. 4 includes a360° camera, mounted to the tip of the index finger. This may be used toidentify the locations of welds to be inspected. A couplant, or oil,dispenser 80 is provided on the tip of the little finger, enabling theuser to place a layer of fluid on a weld to be inspected using theultrasonic probe 62. A macro camera 72 is provided on the tip of themiddle finger, enabling a user to take pictures of any areas that aredeemed interesting, for example based on inspection using the ultrasonicprobe.

Finally, the hand-mounted inspection system further includes acontroller 110, wirelessly connected to the measuring unit and theimaging unit, and a user interface 111, configured to output informationderived from the measuring unit and the imaging unit.

FIG. 5 depicts a further example of a hand-mounted inspection system. Asbefore, a glove-shaped covering 50 is provided that encapsulates atleast the user's hand. The measuring unit 60 includes a thermometer 61and a plurality of position sensors 63 similar to those discussed abovein relation to FIG. 4. The imaging unit 70 includes a wide-angled camera71 mounted on the tip of the thumb. This may be used in conjunction witha fluid dispensing unit in the form of a fluorescent penetrant dispenser81 provided on the tip of the index finger, a fluid absorbing unit inthe form of a wiping sponge 90 provided on the tip of the middle fingerand an illuminator in the form of a ultraviolet light illuminator 100provided on the tip of the little finger in order to apply the penetrantto an area of interest, clean the area of interest and then inspect forresidual penetrant in any cracks.

FIG. 6 depicts a further example of an arrangement of a hand-mountedinspection system. In this arrangement, the imaging unit 70 includes acamera 73 mounted to the tip of each of the fingers and the measuringunit 60 includes plural position sensors 63 configured to measure theposition of each of the fingers, at least relative to each other. Insuch an arrangement, the controller 110 may be configured to combinetogether the images from the plural cameras 73 and generate a singlelarge field of view image to be displayed on the user interface 111.

It should be appreciated that each of the arrangements discussed abovein relation to FIGS. 4 to 6 may be combined with any of the othercomponents of inspection systems discussed in the preceding description.

It will be understood that the invention is not limited to theembodiments above-described and various modifications and improvementscan be made without departing from the concepts described herein. Exceptwhere mutually exclusive, any of the features may be employed separatelyor in combination with any other features and the disclosure extends toand includes all combinations and sub-combinations of one or morefeatures described herein.

We claim:
 1. A hand-mounted inspection system, configured to be mountedon a user's hand, comprising: an imaging unit, configured to provideimages from at least one point of view located on the user's hand; and ameasuring unit, configured to provide data relating to a physicalproperty measured at a measurement location on the user's hand; whereinthe measuring unit includes a sensor configured to provide a measurementbetween two measurement locations, each of the two measurement locationsbeing located on a digit of the user's hand, a tip of a digit of theuser's hand, on the phalanges of a digit of a user's hand, on the palmof the user's hand or on the back of the user's hand.
 2. Thehand-mounted inspection system of claim 1, wherein the measuring unit(60) further comprises at least one of: a sensor configured to measure atemperature at a measurement location on a user's hand; a sensorconfigured to measure a force exerted on a measurement location on auser's hand; a sensor configured to measure the acceleration of ameasurement location on a user's hand; a sensor configured to measureionizing radiation at a measurement location on a user's hand; a sensorconfigured to measure at least one of the direction and strength of amagnetic field and/or an electric field at a measurement location on auser's hand; a sensor configured to measure an eddy current in amaterial in proximity to a measurement location on a user's hand; asensor configured to detect sound waves at a measurement location on auser's hand; a sensor configured to measure the separation between twomeasurement locations on a user's hand; and a sensor configured tomeasure at least one of the voltage, electric current and the electricalresistance between two measurement locations on a user's hand.
 3. Thehand-mounted inspection system of claim 1, wherein the two measurementlocations are located at the tip of the thumb of the user's hand and thetip of a finger of the user's hand.
 4. The hand-mounted inspectionsystem of claim 1, wherein at least two sensors measure or detect at thesame measurement location.
 5. The hand-mounted inspection system ofclaim 1, wherein the imaging unit comprises at least one sub-unitproviding images that is at least one of: a camera; a 360° camera; awavelength filtered camera; a thermal camera; a zoom camera; a macrocamera; a stereo camera; a dichroic camera; and an ultrasound receiver.6. The hand-mounted inspection system of claim 5, wherein at least onepoint of view of images provided by the imaging unit is located on adigit of the user's hand, on a tip of a digit of the user's hand, on thephalanges of a digit of a user's hand, on the palm of the user's hand oron the back of the user's hand.
 7. The hand-mounted inspection system ofclaim 5, wherein the imaging unit comprises at least two sub-unitsconfigured to provide images from different points of view.
 8. Thehand-mounted inspection system of claim 7, wherein the at least twosub-units are a different type from each other.
 9. The hand-mountedinspection system of claim 1, further comprising a covering thatencapsulates the user's hand.
 10. The hand-mounted inspection system ofclaim 9, wherein the covering extends to encapsulate at least a part ofthe forearm of the user and, optionally, at least a part of the upperarm of the user.
 11. The hand-mounted inspection system of claim 9,wherein the covering is formed from a material that is at least one offluid impermeable, gas impermeable, thermally resistant, electricallyresistant and puncture resistant.
 12. The hand-mounted inspection systemof claim 1, further comprising a fluid dispensing unit configured tosupply a fluid from at least one dispensing location located on theuser's hand.
 13. The hand-mounted inspection system of claim 12, whereinthe at least one dispensing location is located on a digit of the user'shand, on a tip of a digit of the user's hand, on the phalanges of adigit of a user's hand, on the palm of the user's hand or on the back ofthe user's hand.
 14. The hand-mounted inspection system of claim 12,wherein the fluid dispensing unit is configured to supply at least oneof oil, a liquid penetrant, an air jet and a water jet.
 15. Thehand-mounted inspection system of claim 1, further comprising a fluidabsorbing unit configured to absorb fluid at a location on at least oneof a digit of the user's hand, a tip of a digit of the user's hand, onthe phalanges of a digit of a user's hand, the palm of the user's handand the back of the user's hand.
 16. The hand-mounted inspection systemof claim 1, further comprising at least one illuminator, configured toemit at least one of visible light, infrared and ultraviolet radiation.17. The hand-mounted inspection system of claim 16, wherein theilluminator is located on a digit of the user's hand, at the tip of adigit of the user's hand, on the phalanges of a digit of a user's hand,on the palm of the user's hand or on the back of the user's hand. 18.The hand-mounted inspection system of claim 1, further comprising acontroller, configured to receive data from at least one of the imagingunit and the measuring unit and to output corresponding information to auser interface.
 19. The hand-mounted inspection system of claim 18,wherein the user interface comprises at least one display configured todisplay an image based on data from the imaging unit.
 20. A method ofinspecting and/or servicing a machine, optionally an aircraft engine,comprising: mounting the hand-mounted system of claim 1 on a user'shand; and inserting the user's hand into the machine.